Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 19: Symposium Spin Effects in Semiconductors of Reduced Dimensionality

HL 19.3: Invited Talk

Tuesday, February 26, 2008, 11:30–12:00, ER 270

Nonequilibrium nuclear-electron spin dynamics in semiconductor quantum dots — •Fritz Henneberger and Ilya Akimov — Humboldt-University Berlin, Institut für Physik, Newtonstr. 15, 12489 Berlin, Germany

Optical spin pumping and the hyperfine dynamics is investigated in the situation where the spin of a localized electron interacts only with a few hundred nuclear moments in the surrounding lattice. Both pumping and read-out of the spin state is accomplished via the trion feature. The formation of a dynamical nuclear polarization as well as its subsequent decay by the dipole-dipole interaction is directly resolved in time. Because not limited by intrinsic nonlinearities, polarization degrees as large as 50 % are achieved, even at elevated temperatures. The data signify a nonequilibrium mode of nuclear polarization, distinctly different from the standard spin temperature cooling concept.